/**
 * Copyright 2011 FeedDreamwork SIG
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package org.feeddreamwork.feed;

import java.net.*;

import org.feeddreamwork.*;
import org.w3c.dom.*;

public abstract class FeedParser {
	public abstract boolean isThisType(Document source);

	public Feed parse(Document source) throws FeedParsingException {
		return parse(source, null);
	}

	public abstract Feed parse(Document source, String baseURL)
			throws FeedParsingException;

	protected String resolveURL(Node node, String url, String baseURL)
			throws FeedParsingException {
		if (Utils.isAbsoluteURL(url) || Utils.isNullOrEmpty(baseURL))
			return url;
		try {
			return Utils.resolveURL(url, baseURL).toExternalForm();
		} catch (MalformedURLException e) {
			throw new FeedParsingException();
		}
	}

	protected abstract Feed parseFeedMetadata(Element root, String baseURL)
			throws FeedParsingException;

	protected abstract Entry parseEntry(Feed feed, Element entry, String baseURL)
			throws FeedParsingException;
}
